Pumping or compressing of gases



mamas i OFFICE rename on comassnvc or cases Amerigo F. Caprio, Newark,N. 1., assignor to celluloid Corporation, a corporation of New Jersey NoDrawings Application April 22, 1936, erial No. 75.785

2 Claims. (CL 252-53) .l'his invention relates to a lubricant for gashandling pumps, gas compressors, gas meters, etc., and especially to alubricant that does not iorm explosive mixtures with gases and which maybe safely employed in the pumping of gases intended for medicinal uses.This invention relates more particularly to the use of organic esters ofphosphoric acid for the purpose of reducing friction of moving parts onmachinery adapted for handling gases.

An object of the invention is to effectively and safely lubricate gashandling devices. Another object of the invention is the method ofcompressing or pumping oxygen under such conclitions that the formationof explosive mixtures 1 of gases and lubricant is obviated. A stillfurther object of the invention is the compression of gases intocylinders in such a manner that the compressedgas is in a purer statethan has heretofore been possible. Other objects of the invention willappear from the following detailed description.

Relatively pure gases are compressed in containers, which containers mayor may not contain absorbent materiaL'for distribution to consumers. Theproblem of compressing these gases into the containers has involved,prior to the present invention, serious diiilcultles. One of the majordimculties was the lubrication of' pumps and compressors. cants, whenemployed in compressors and pumps which attain an elevated temperature,tend to volatilize and are carried along with the gases into thecontainers, thus producing impure products. the heat and pressure ofpumping action and when handling gases containing oxygen they formexplosive mixtures. For example, mineral oils. when used on pumpshandling oxygen, formed explosive mixtures. Such mineral oil lubricantswere therefore replaced by water, water and glycerine, and watercontaining soap or soap and glycerlne. These aqueous lubricantsobviously caused very serious difficulties in the packing of the pumpsand compressors and in operation thereof. Moreover, at the temperatureand pressure at which thepumps and compressors are operated, theseaqueous lubricants were particularly unsatisfactory since the water,constituents of the soap, and oftentimes the glycerine evaporated intothe stream of gas and were carried into the storage cylinder. Theadulterants contained in the gas often gave to the gas an cliensiveodor. Furthermore, the presence of water or other reactive compounds incontainers con- Many of the ordinary lubri- Other lubricants tend tovolatilize under taming oxygen often caused the gas to react corroslvelywith the material of walls of the container making them weak anddangerous to handle. v

I have now found that the lubricants heretofore employed in gas handlingdevicesmay be replaced by an organic phosphate. These and phosphates,particularly the aryl type, have a low vapor pressure, are odorless andnon-reactive. They, therefore, have the advantage over prior lubricantsin that there is relatively no volatilizatlon of the same and the smallquantities that may be carried into the gas do not give rise tocorrosion of containers or oflensive odors. Furthermore, the arylphosphates are substances having an oily quality and their lubricativevalue is equivalent to that of mineral oil. They have a high wettingproperty which causes them to always maintain a film on the surface ofthe par-ts to be lubricated. Due to the presence of the film the pumps,compressors, etc., are always sealed against leaks.

By employing this invention, massive and clumsy sealing means need notbe employed in pumps and compressors as was necessary when water formedthe chief lubricant, This invention permits of the use of a more simpledesign of pump, compressor, etc., thus reducing greatly the overheadcost of plants adapted to handle gases. The life of the machinery isalso greatly increased when employing the aryl phosphate as thelubricant as it forms a fllm over the metal parts preventing rust andcorrosion, whether the pumps are in use or not. For the purpose ofdescribing this lnvention and in the appended claims, the term pumpingmachines are intended to cover suction pumps, compressor pumps, metersor other types of gas handling devices which employ moving parts whichrequire lubrication. i

In accordance with my invention, I pump, compress or-otherwise handlegases in devices employing moving parts, which moving parts arelubricated and sealed against gas. leakage with an organic phosphate.able to compress gas into cylinders or other stor age chambers, whichgas is free of contaminating gas formerly found therein due tovolatilizetion of the lubricants employed in the machines. Also, inaccordance with my invention, I pump gases containing oxygen in such amanner that no explosive mixtures are formed.

This invention is applicable to the pumping of such gases as sulphurdioxide, carbon dioxide, carbon monoxide, methyl chloride, anhydrous Inthis manner I am ammonia gas, oxygen, hydrogen, methane, eth ane,ethylene, acetic acid vapors, acetone vapors, etc. Other types of gasesand also vapors may be pumped in accordance with this invention. For thepurpose of condensing, reclaiming and during the manufacture oi suchliquids as acetone, acetic ,acid and the like, the lubricant of thisinvention may be employed in the machinery handling the substances inthe vapor stage.

Any suitable aryl phosphate may be employed as the lubricant. Formedicinal purposes, that is, for gases to be used for human consumptionor in or around ioods intended-for human consumption, it is advisable toemploy as the aryl phosphate a tricresyl phosphate prepared in themanner described in application S. No. 708,475 iiled January 26, 1934,or application S. No. 718,436 filed March 31, 1934. Although trloresylphosphate as described in the above applications is preferable where thecompressed gas is to be employed for medicinal or human consumption,other aryl phosphates may be employed where the gas is to be used forindustrial purposes. Any of the aryl phosphates named in and prepared inthe manner described in'U. S. applications S. Nos. 106,869, nled January12, 1934; 717,954, :died March 29, 1934; 720,448, filed April 13, 1934;and 50,714, filed November 20, 1935, may be employed.

While I prefer to employ those esters of phosphoric acid which arerelatively non-volatile and non-inflammable, such as tricresyl phosphate(various isomers and mixtures or same), tri-, phenyl phosphate, mixedcresyl and phenyl phosphate, trixylenyl phosphate (various isomers andmixtures of same), trinaphthyl phosphates, etc., it is to be understoodthat other organic phosphate esters may be employed which are somewhatmore volatile and inflammable than those listed above. For example, insome compressors which operate at very low temperatures a mixture ofalcohol and glycerine has been used as the lubricant. Glycerine isobjectionable because it aids corrosion, is water soluble and becomesgummy. For these compressors a mixture of alcohol and tricresylphosphate may be employed inaccordance with this invention.

While the aryl phosphates are preferred, 1 may employ alkyl phosphateesters or mixtures of these with a-ryl phosphate. Examples of allrvlphosphate esters are triethyl phosphate, trimethoxy ethyl phosphate,tributyl phosphate,

chlorinated to various degrees.

aoszasc esters described in U. 8. Patent No. 1,982,903 and in Patent No.1,994,530. The chlorinated phosphate esters may also be employed inaccordance with my invention, such as tricresyl phosphate Also thephosphite esters, such as tricresyl phosphite and triphenyl phosphate orthe thiophosphates may be employed alone or in combination with any ofthe Y other esters listed above.

In certain types or compressors it may be advantageoous to mix with' thephosphate ester small quantities of mineral oil 01' the paraffln seriesor other lubricants, such as dichlormethyl stearate. The combination ofaryl phosphates with chlorinated diphenyls and chlorinated naphthalenesare also comprised within the scope of this invention. Oxygen inhibitorsmay also be added to the lubricant such as small quantities, say.(ll)1%,oi alpha or beta naphthol.

The aryl phosphate may be employed in a manner similar to mineral oil,and, if desired, may be thickened with soaps, greases, etc., for use indevices requiring a composited lubricant. By employing this invention,oxygen and other explosive gases may be handled with apparatus normallyemployed in the compression of air, and no expensive devices need beemployed for maintaining the moving parts lubricated. The pumps,compressors, etc., employed may be water cooled or where the pump isacting as a suction pump, the pumps may be warmed by any suitable means,such as jackets surrounding the pumps wherein suitable medium may becirculated.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patentis:

1. Method oi lubricating bearings of meters, without corrosion ofbearing metals over periods of time, comprising applying to suchbearings a lubricant consisting essentially of a non-volatile ester ofphosphoric acid.

2. Method of lubricating bearings of meters, without corrosion ofbearing metals over periods of time, comprising applying to suchbearings a lubricant consisting essentially of tricresyl phosphate.

AMERIGO F. CAPRIO.

